1. Field of the Invention
The present invention relates to electromagnetic systems for reducing, eliminating and/or monitoring vibration in variable-state mechanical and/or industrial structures. The invention also relates to an electromagnetic actuator for use in connection with industrial equipment and other apparatuses. The invention also relates to a vibration control system that is dynamically responsive to changing physical and/or environmental characteristics (position, mass, rate of throughput, etc.) of the controlled structure.
2. Discussion of the Related Art
U.S. Pat. No. 5,796,849 (Coleman et al.) refers to a system for actively controlling noise and structural vibration. The Coleman et al. patent relates to situations where the dynamics of the transfer functions between the actuator devices and the residual sensors change over time. In the Coleman et al. system, a probe signal is used to obtain a current estimate of the plant transfer function. U.S. Pat. No. 5,816,122 (Benning et al.) refers to a system for controlling echo-like responses to mechanical disturbances. The Benning et al. system provides for adaptive suppression of vibrations in metal-cutting equipment. In particular, the Benning et al. patent discusses specific techniques, involving boring bars and subtractive shaping of a rotating workpiece, for actively suppressing vibration in a movable machine tool. U.S. Pat. No. 5,713,438 (Rossetti et al.) describes an adaptive feedforward system for controlling vibration of an aircraft fuselage or automobile structure. The Rossetti et al. system does not employ feedback control together with feedforward control, and it does not involve measurement of plant transfer functions. The Rossetti et al. system employs shaker-type electromagnetic elements, which can be difficult and expensive to install and maintain, and which are prone to nonlinear behavior and harmonic distortion. The Coleman et al., Benning et al. and Rossetti et al. patents are discussed in more detail below.